Fiber Bragg grating sensors are becoming increasingly popular and attractive for biomechanics and rehabilitation applications due to their advantageous properties like small size, light weight, biocompatibility, chemical inertness, multiplexing capability and immunity to electromagnetic interference. FBG sensors have been utilized in a variety of different applications, such as aeronautics, automotive, civil engineering structure monitoring and undersea oil exploration. The use of fiber optic sensors for biomechanics and rehabilitation applications is very recent. The full-scale implementation has not been done yet.
FBG strain sensors can be used to measure strain in bones, stresses in intervertebral discs, pressure distribution in Human Machine Interfaces (HMIs), forces induced by tendons and ligaments, shrinkage stresses in bone cement during polymerization. FBG displacement sensors could be used to measure chest wall deformations, angles between body segments during gait. FBG sensors are especially useful in dental biomechanics.
Applications of fiber Bragg grating sensors in biomechanics and rehabilitation engineering:
- Monitoring of biomechanical behavior of the musculoskeletal system;
The measurement of strain on the bones is crucial for understanding bone diseases and in designing medical devices. The measurement of bone strain is conducted using an FBG strain sensors, which helps to study the effects of fracture fixation plates. FBG strain sensors can also be used to understand to what extent the bone calcium loss affects strain response of bone
- Strain measurement of bone cement;
Damage to bone cement caused by dynamic loading is one of the main causes of hip replacement failures. The studies of human bone models using FBG strain sensors could be useful to verify the action of the cement, both during the curing process and after consolidation.
- Pressure mapping and the measurement of contact forces and stresses of orthopedic joints;
The understanding of contact stress at orthopedic joints is necessary for prostheses research and biomechanics studies. Due to the flexibility and multiplexing capability, FBG sensors are suitable for irregular-shaped interface surfaces, like a knee joint.
- Measurement of pressure distribution at the intervertebral disc;
FBG pressure sensors have outperformed other means of measuring pressure distribution at the intervertebral disc due to the small size and biocompatibility.
- Dental biomechanics;
FBG sensors are already used in dental applications, for example, monitoring the force and temperature as a function of time in dental splints worn by patients suffering from sleep apnoea.
- Monitoring of chest wall movement during respiration.
The studies of biomechanics have benefited greatly from the implementation of FBG sensors to measure chest displacement during respiration. The FBG sensors are embedded into a chest deformable strap which is strained in accordance with the deformation of the chest.